Pharma & Specialty Chemical Standards

Cystine, the IUPAC name (2R,3S)-2-amino-3-(sulfanylmethyl)propanoic acid dimer, has molecular formula C₆H₁₂N₂O₄S₂ and molecular weight 240.29 g/mol. It belongs to the disulfide class of amino acids, characterized by an intermolecular disulfide bond between two cysteine residues. Therapeutically, it is utilized in dermatological formulations and as a precursor for glutathione synthesis. Key physicochemical properties include low water solubility, high melting point (240°C), and zwitterionic character. Its mechanism of action involves redox cycling via disulfide bond cleavage to cysteine, supporting antioxidant defense systems and protein disulfide isomerase activity in cellular processes.